MicroROS on Espressif

[hierophect]

This draft PR is an attempt to add MicroROS as an optional addition to the Espressif port. The Robot Operating System (ROS and sucessor ROS2) is a very commonly used collection of software and standards in professional and research robotics. It is somewhat misnamed: it is not an operating system or RTOS, but a collection of middleware and type standards for different robot parts to talk to each other. MicroROS is an API for embedded systems that allows them to talk to a ROS system on a linux machine, such as a big computer running perception, kinematics or machine learning tasks.

https://micro.ros.org/docs/overview/hardware/

The goal of this project is to allow Espressif Circuitpython boards to recieve and transmit data over WIFI to a computer running ROS, to publish sensor data, take in motor commands, and other tasks. The secondary goal of the project is to prevent as much of ROS's extreme complexity as possible from entering Circuitpython's build system (native ROS is not beginner software and has many tricky requirements). I'm focusing on the latter to start, to try and see whether this project is possible/practical before designing a full API.

Questions / priorities:

• Since ROS is not a priority for most Circuitpython users it probably makes sense to make this either an optional build flag that is user-compiled. Alternatively, it could be an "alt board" build for some specific Espressif boards with high utility, like the Feathers.
• This project uses the Espressif MicroROS component, which requires ROS-specific build tools to compile (colcon and ament). To avoid adding these to CI I've pre-compiled the component and included it as a .a library. However this does make the project more difficult to keep up to date - I'm not sure what the best option is here?
• MicroROS is also supported for STM32 boards and could potentially be added later, so I'm not sure if the bindings for this project are better placed in ports/espressif/bindings or shared-bindings
• The include additions are kind of insane, maybe could be either broken off into a separate repo, or whittled down to a more circuitpython-specific subset.

In the off-chance that anyone has actually used ROS and has specific concerns or API requests, they'd be great to hear, so far I'm just going off suggestions from people in my personal robotics network.

Will resolve #8139

[tannewt]

Where do these microros-ext files come from? Can you submodule them instead?

[hierophect]

I agree we should submodule somehow - microros-ext is sourced from https://github.com/micro-ROS/micro_ros_espidf_component, which I avoided including directly due to the additional requirements in the idf virtual environment, pip3 install catkin_pkg lark-parser colcon-common-extensions empy==3.3.4, and the extended build process caused by colcon fetching all the message type packages. I didn't want them clogging up Circuitpython's CI process, but @dhalbert suggested it might not be a big deal to include those directly, as long as the component isn't enabled willy-nilly. I'm happy to either include it directly and refactor the build system changes, or make a submodule of the precompiled version to use instead.

[tannewt]

I don't understand the build stuff you are referring to. A README.md in microros-ext would be helpful in explaining where it came from and how to update it.

[hierophect]

I don't understand the build stuff you are referring to.

Sorry, let me say that in a less confusing way. Compiling the MicroROS component installs a bunch of python package managers, is slow, and has a lot of verbose build output. To avoid adding that to Circuitpython's CI tests, I made a pre-compiled version, which is what I've included. I've recieved feedback already that that might be less easy to maintain, so I could revert back to including the original component as a submodule if you feel this feature being more futureproofed would be worth a small performance hit to the CI. Which would you prefer?

[tannewt]

How about splitting the difference and making a separate repo for the precompiled files? That way it isn't in CP but it doesn't require building every time.

[furbrain]

I'd just like to comment that this looks awesome, having ROS on CircuitPython could open up lots of opportunities. I'm currently thinking of making a CircuitPython sensor -> ROS factory utility class - so you could just set up your sensor, pass it into the class and it starts publishing on an appropriate topic - so an accelerometer+gyro would start publishing IMU messages for example.